In civil engineering or in mine industry, the roof is often supported by bolts or cable bolts to prevent the roofs from collapsing. One known procedure as illustrated in FIG. 1 for supporting the roofs 10 is to drill a bore 12 in the roof 10 to secure a high tensile roof bolt 14 in the bore 12 in a stable position. The roof bolt 14 carries a support plate 16 engaged with the roof surface on the outer end portion of the bolt. The inserted portion of the bolt 14 is normally a steel rebar or strand 18 having an end fixed to the roof 10. In these applications rolled wires with a surface partly deformed or indented are preferred. Indeed, the formed ‘rough’ surface assists the bonding agent to effectively bond with the stands. Such strands are typically favorable to establish a good anchorage with their surroundings via resin, such as strands in civil engineering to obtain a satisfactory anchorage concrete and strands for mining to create a satisfactory anchorage with the rock.
A problem accompanying with the application of strands is that steel wires tend to rust when subjected to conditions, such as in a humid or acid atmosphere that enhance corrosion.
A common solution to prevent corrosion of steel wires is to provide a protective coating on the surface. In order not to adversely influence the other properties of the wire, such a coating is by preference metallic. Most preferred coatings for steels in this respect are zinc or zinc alloy that are applied through a hot dipping process onto the steel wire surface. Intermediate alloy layers are formed during the hot dipping process ensuring a good adhesion of the coating to the steel wire. Such coatings provide a sacrificial corrosion protection to the steel.
However, there are no strands in the market for this application made of steel wires having surface deformation or surface contour curvature and corrosion resistant coatings. The application of corrosion-resistant coatings on the surface of steel wires will smooth the surface and fill the deformation and thus this is detriment for the bonding efficiency and the anchorage of the strand. In this respect, there is a demand for a strand having still the desirable profiles on the surfaces and in the meantime having corrosion resistance.